Posted
by
simoniker
on Monday January 12, 2004 @02:18PM
from the no-more-whooshing dept.

Rommel writes "NewScientist.com is reporting that the cause of the leak in the International Space Station has been found and fixed. The leak was found in a hose in the Destiny lab module. The hose was used to equalize pressure and eliminate fog between two panes of a window. While the leak was so slow it was unlikely to pose a direct threat to the crew for months to come, some equipment on the ISS is only certified to operate above a certain air pressure. The leak was originally mentioned on Slashdot a few days back."

This is actually a bit frightening when you think about it. If it took them nearly a month to find this problem imagine if it were a much more serious threat. You would hope that the station would have sensitive enough monitering equipment to detect where problems are occurring. I would probably think twice about spending my powerball winnings on a vacation to the ISS and wait till the Hilton is on the moon,...no not Paris you dirty minded/.er, although 0-Gravity sex......nevermind.

Other space news sources (like Spaceflight Now [spaceflightnow.com]) mention the fact that the leakage was already known late last year, dec 29 IIRC. Maybe your parent knew that. Then again, that still makes it less than half a month.

A bigger leak would definitely be easier to find. For a medium-sized leak (the kind that would drain the station over the course of a day or two), the sound would be loud and easy to find; most likely a whistling, rushing sound.

For a very large leak, just look for the impact damage where equipment and bodies slammed hardest against the surrounding hull sections.

Not even all that uncomfortable. IIRC, NASA originally planned on only pressurizing space capsules to around 5psi or pure oxygen. This is the same as the partial pressure of oxygen in our atmosphere, so the astronots didn't get high on O2 or anything. That's why the Apollo 1 fire was so bad.

Of course, I think the ISS uses normal 14.7psi of normal earth air, so they'd have to make the air a lot more Oxygen rich if there was a leak. Anyways, just my 2 cents.

A small correction on the Apollo 1 fire. The fire hazard from low-pressure pure oxygen is comparable to the fire hazard from a full-pressure atmospheric mix. I believe there are physiological effects to low-pressure oxygen that make it less desirable.

What happened with Apollo 1 is that it was supposed to use low-pressure pure oxygen in flight. However, on the ground, they couldn't do that because the capsule was only meant to take pressure pushing out. If they had used low-pressure oxygen on the ground, it would have been crushed by the outside air. So they just increased the pressure. Oxygen at 3psi is ok, but oxygen at 16psi is an incredible fire hazard. Fire starts, everybody dies.

That is absolutely correct. Even human flesh will burn in pure oxygen, despite the water content, as will many metals and most plastics.

It is interesting that the fire hazard rises rapidly just above the normal atmospheric partial pressure, which is the optimum for organic life as we know it. But, as you imply, you can take away the nitrogen and the odd bit of Argon and CO2 without tangible effect.

I never did understand how the crew were supposed to cope with breathing a full atmosphere of oxygen anyway, it

Actually the crew could work normally until about 1/2 of an atmosphere. If the change is gradual enough, your body build up extra red-blood cells to compensate. Mountain climber in the Himalayas actually park at camp for about six weeks to 'acclimatize' to the reduced atmosphere.

Most people would still need some bottled Oxygen to get up to the top of Everest though, at around 1/3 of an atmosphere. When the pressure gets that low, your body has trouble metabolizing fast enough to maintain temperature.

I was reading a good page on low-pressure physiology (had to do witk HALO skydiving) where they did the calculations and figured out you're about equally screwed with or without O2 on Everest - if you don't bring O2, you're naturally sluggish and slow, but if you do, you have a hard time getting enough extra energy to make up for the extra weight you have to carry. There is a "sweet spot", but go very far outside of it and you might as well just breathe the thin air.

The truth is that above around 26,000 feet there is no amount of acclimatization that will compensate for the diminished oxygen/pressure. That's why they call it the "Dead Zone;" because essentially, you're dying. What happens is your cells start to deteriorate, becoming unable to contain fluids. Your brain starts to swell from the uncontrolled fluid buildup (High Altitude Cerebral Edema). Your lungs begin to do the same (High Altitude Pulmonary Edema). The only fix is oxygen and pressure.

When you get above around 30,000 feet, you start running into funny little things like needing the air/oxygen forced into you with positive pressure, rather than the kind of "on-demand" oxygen setups that are commonly used. If I remember correctly, this is related to pressure; but is not the same issue that you get with pressure higher up, where you're worried about the blood's ability to contain its nitrogen, and thus, about the blood boiling.

where you're worried about the blood's ability to contain its nitrogen, and thus, about the blood boiling.

I think that's only issue when pressure goes lower rapidly. As long as pressure goes low slowly enough, the nitrogen can get out of the blood slowly, and you avoid those potentially lethal nitrogen bubbles in the blood.

It's same thing with diving, professional divers sometimes stay in high pressure for days (either at the bottom of a sea, or resting in a pressure chamber), then when the work is don

I was told, second-hand, the story of a NASA contractor who was in a meeting with some NASA engineers. As all geeks should know, hard drives require air pressure to work (floating heads and all that). When the subject of a loss of air pressure on the ISS came up, one of the NASA engineers started talking about how all the experimental data would be lost because the HD's would fail. It wasn't until the contractor said "Uhhh, what about the crew?" that they had even entered folks' minds about being similarly sensitive to a loss of air pressure.

No, just the fact the crew is 'rated' to lower pressures for operation. There is a flight reg for a repress to 14.4 psia if the pressure drops to 13.9. The 13.9 is not the crew danger redline. There are several pieces of equipment on board that have the lower pressure operational limit set at 13.9... ie thats as low as they are certified to work with no problem. at 13.95 or so they start to be powered down in case the pressure continues to drop.

The reason is due to thermal buildup. Without gravity you have no coreolis effect, most commonly recognised as the idea that hot air rises. In ziggy hot air does not rise it just gets hot, thus you have to have thermal transfer by contact of some sort, IE air blowing or contact with a heatsink ( water loop ) etc... which is the reason for those huge radiators on the station.

At lower pressure there is less thermal transfer with the air which means greater heat buildup in the electronics could cause a problem or possibly an unrecoverable malfunction.

Genrenally speaking these limits are VERY CAUTIOUS. Much of the equipment has no redundancy and could only be replaced by flying it up from the ground... something very difficult to manage payload scheduling wise even if shuttle were making flights and next to impossible with Soyuz/Progress launches. Thus you don't risk even the possibility of an equipment failure even though much of the equipment would likely operate just fine in near vacume conditions.

To have an idea regarding crew limits consider the fact suit pressure for EVA's is 4.3-5 psia, the new hard suit concept allows for 8.3 ( no pre-breathing ). Either consisting of an environment which could be created in very short order on the station. Of course this requires shifting the concentration of oxygen... close to 100% in the case of the 4.3 I belive, which is dangerous. The 8psia range requires ~32psia which is only a few percentage points above nominal environment on the station.

Thus the pressure drop at that slow of a rate presented a far more immediate danger to the equipment than it did to the crew. The crew was not worried nor were the flight control teams worried about the crew for the simple reason the crew was as yet not in any immidiate danger as it would have taken weeks at the recorded rate of loss to place the crew in danger just had they not undertaken to replace what was lost... they also have plenty of spare oxygen to add and thus it would have taken months for this leak to depleat stores to the point where the crew would have been at risk.

The engineers didn't have the head in the clouds or no concern for the Crew. Crew safety on the station takes precedent over EVERYTHING else.

Just to nitpick, the coriolis effect has absolutely nothing to do with gravity or rising gases. Its a "fictious force" that occurs as a result of observations taken in a rotating (ie not an inertial system) reference frame, such as the rotating earth.
In everyday life, you do not experience any coriolis effect; if you did you would be aware that the earth is rotating under you- Instead, you're probably confusing the coriolis effect on global mases of air, which results in circulation cells that span vast

Hot air rising affected by the coriolis effect creates weather. Our teacher used a demonstration with a pot of water and stated the forces at work with the water boiling was the coriolis effect.... DOUGHT !!! Or perhaps I wasn't paying very close attention, actually I rather hope that was the case.

One thing that requires very close to atmospheric pressure is hard drives. The heads float above the platter utilizing the bernouli principle. If the pressure too high, the heads get pulled down onto the platter (bad). If the pressure is too low, the heads don't get sucked down close enough, and data can't be read or written with any reliability.

For reference, look at the environmental specifications of any hard drive to see what pressures (often expressed in altitude above sea level) can operate under.

according to the article The station's air pressure had dropped from the normal 14.7 psi to 14.0 psi.
NASA have emphasised that the crew's health was not in danger, but some onboard equipment, including an air monitor, is only certified for use above 13.9 psi
it would seem that things were pretty close. but keeping in mind that it was only losing.03 psi per day it doesnt seem that serious. they would have had 33 more days to find it atleast.

"The news couldn't have come at a better time," mission control told the crew.

This is the kind of thing that makes no sense and must just be there to meet the word count requirements. Here are some "better times" that this could have come: Yesterday, two days ago, the day the leak was discovered.

this is a phrase used in the English language that means "just in the nick of time," or "at the last possible second." It isn't meant to be interpereted literally, kind of like peanut-better isn't butter with peanuts in it.

What? I think that people who write articles are only supposed to use words that have meaning. I'm going to make a guess that you don't write professionally, as anybody who had the gall to charge for their writing would not say something like that. "Oh, those are just words..."

"The spacecraft has apparently been taken over - "conqured" if you will - by a master race of giant space ants. It's difficult to tell from this vantage point whether they will consume the captive earth men or merely enslave them. One thing is for certain: there is no stopping them; the ants will soon be here. And I for one welcome our new insect overlords. I'd like to remind them that as a trusted TV personality I could be helpful in rounding up others to toil in their underground sugar caves." - Kent Brockman

My 1990 Pontiac Sunbird has a leaky sunroof. I can't decide what my favorite thing about that is:
* That is dumps water on the top of my head while I'm trying to drive.
* Dumps water on my lap so it looks like I peed my pants.
* When the resulting moisture inside the car ends up on the inside of the windshield. Then freezes. Then when I scrape it off it's like it snowed in my car.

CAPE CANAVERAL, Fla. - The $1.4 billion U.S. Destiny lab opened for business at the International Space Station Sunday, cracking the hatch on a new era of scientific discovery that one day could lead to human expeditions beyond Earth orbit.

US mission commander Michael Foale and flight engineer Alexander Kaleri repaired the crack soon after it was discovered in the US module early on Monday, the officials told news agencies.

Michael Foale [nasa.gov]: considers Cambridge, England to be his hometown & came to the U.S. in '83Alexander Yurievich Kaleri [nasa.gov]: Special Honors: Hero of the Russian Federation[Insert Soviet Russia Jokes Below]

With reduced pressure, the thermal capacity of the cooling air is proportionally reduced. Combined with changes in forced air flow and microgravity not creating convectional cooling, you can have long-term overheating issues with equipment that consumes very little power.

This is solved on satellites with conductive cold/hot plates, but that results in much heavier equipment.

Regarding leakage rates, it's very difficult to estimate leak flow rates. The flow might be proportional to pressure squared, or cubed. If it's in an elastic seal, it may completely re-seal when the pressure drops to a specific level.

Humans can function at elevations of about 5psi (see the other posts about mountain climbers), and survive on a little less. Since O2 is less than 20% of the atmosphere, you can theoretically live on 1psi of pure O2. But secondary effects are killers at that low pressure, such as keeping enough moisture in the lung tissue. When near-pure O2 is used, it is usually at about 3psi or nearly the partial pressure of O2 at sea level.

A replacement hose may be flown up to the station later in January on a Progress vehicle.

Egads, not even a spare hose. I guess it's a non-critical part but it still seems kinda lame.

It would be common sense that many of the hoses on various equipment would be the same. Then you'd have a bunch of spare hoses to repair all sorts of things. Or maybe I'm not thinking enough like an engineer.

"The leak was made more worrisome because the main oxygen generator, which has been working only sporadically, failed again last week. Russian flight managers are designing a way to fix it this week with spare parts already on the station."

Shouldn't the OXYGEN generators be...oh I dunno...WORKING most of the time? Failed again last week reminds me of the infamous furnace fighting scene from a Christmas Story.

I can just see a Russian cosmonaut banging on it with a wrench cursing...

The first crew of the Salyut 1 space station were returning on Soyuz 11 [vt.edu] when a pressure equalization failed - possibly because of the shock of the explosive bolts that separated them from the station. That one must have been a much faster leak, since they only had a chance to get it closed half way before they died. Yeah, the leak in this case wasn't anything drastic, but how much air was that valve capable of releasing? How much time would the crew have had to either fix it or abandon the station if it

Maybe I'm wrong, but I seem to remember that when the last shuttle disaster occured, there was no contingency for docking with the Space Station in case of trouble. That itself seems like a HUGE design flaw. I hope this is wrong, because it would mean that the shuttle could not rescue people trapped on the Space Station either.

Is it true that only spacewalks and cargo transfers occur between these two specific orbitals?
Yeah, a manned-mission to Mars is looking more feasible every day . . .

Getting around in space isn't like getting around a subway system. You can't just jump orbits. You have to know where you're going, and go there at launch, when you're pouring the enormous impulse into the vehicle. The ISS is at a very high inclination orbit in order to be reached by both Russian and American launch facilities. This orbit is a very "expensive" one in terms of energy at launch. Which means less payload.

Space is a very, very big place, and the shuttle (like any space vehicle that isn't mostl

Yeah, but just think of all the tubing, wall panels, airlocks, windows, and god knows what else that had to be check. And especially since it was a leak in a piece of tubing, I'm surprised they found it so fast.

I think it's interesting that initially the Americans tried to point the finger of possibility at just about anything capable of leaking built by the Russians, who of course have a zillion more years of experience building these things than we do...

References?

I recall both sides saying they had no idea where the problem was and that they were looking for it. I don't recall anyone placing any blame ahead of time, except perhaps for some slashdot trolls.